If you want yo can change over to braided at the ends of the steel lines then that will give you some
flex and vibration resistance ... use compression fittings on the steel
That's the direction I've decided to go. Need to see what fittings I have on hand, plus don't believe there's enough -6 line left to do the job.
I would highly recommend Teflon (Aeroquip TFE style) hose and fittings for that application. Trans fluid is nasty and the rubber/stainless braid stuff will degrade over time.
Steel tube can be flared and assembled with nut/sleeve type fasteners. We've done that with 5/16" line using -5 AN stuff. 3/8" goes to -6.
